This disclosure relates generally to applying a coating and, more particularly, to applying a coating to a perforated surface.
As known, gas turbine engines, and other turbomachines, include multiple sections, such as a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. Air moves into the engine through the fan section. Airfoil arrays in the compressor section rotate to compress the air, which is then mixed with fuel and combusted in the combustor section. The products of combustion are expanded to rotatably drive airfoil arrays in the turbine section. Rotating the airfoil arrays in the turbine section drives rotation of the fan and compressor sections. The hot gas is then exhausted through the exhaust section.
Some turbomachines include perforated, cylindrical liners. An augmentor liner within the exhaust section is one type of perforated, cylindrical liner. The augmentor liner establishes a passage between an inner cylinder and an outer cylinder. Cooling air, obtained from the compressor or fan, flows through the passage and through perforations within the inner cylinder. The air moving through the passage and through the cylinders facilitates removing thermal energy from this area of the gas turbine engine.
During assembly of the augmentor liner, the surfaces of the inner cylinder that will be exposed to the hot air are typically coated with a thermal barrier coating. The inner cylinder is then laser drilled to create perforations. If the thermal barrier coating extends into the perforations, the thermal barrier coating can block air movement through the perforations.